The Kenya Pearl Oysters.

Abstract

This report provides a brief description of the pearl shell trade and the occurrence of pearl oyster species between Shimoni and Malindi, in Kenya and the population densities and structure of the most important commercial species, Pinctada margaritifera L from preliminary data collected in 1998 and 1999. Pinctada margaritifera L, and Pteria chinensis Leach, were widely distributed in the study area. The species, Pteria penguin Roding, only occurred in the Wasini Channel in Shimoni. P.margaritifera population density was highest in shallow sites dominated by seagrass within Gazi Bay. Pooled population density data showed that the oysters were more abundant in shallow water, less than 5 m depth. Most of the individuals in the samples were between 10 to 60 mm in size. The largest individual was 123 mm and was collected from a sheltered reef in Shimoni. There were more males than females and the mean size of females was larger than that of males. The size at first maturity of males was smaller than that of females. The proportion of males was higher in small-size class oysters and lower in large-size classes. These reproductive adaptations appear to be a strategy to sustain the oyster population.